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Sleep Well: Your Psychological Health Depends On It

May 4, 2019

 

There is some truth to the phrase “waking up on the wrong side of the bed.” When I don’t sleep very well, I will probably be much more affected by seemingly minor mistakes than other times. For example, I might be particularly self-critical of a research presentation, ruminating on the negative aspects and failing to acknowledge anything positive. The recurrent thought of poorly answering a question might leave me feeling disappointed. In contrast, I will probably fail to retrieve the memories about the questions that were answered well or the clarity of concepts explained. Cognitive neuroscientists have linked poor sleep to poor psychological health at the neural level, particularly involving a brain structure called the amygdala.

The amygdala is an almond-shaped brain structure that modulates emotional reactivity. When sleep deprived, amygdala function is perturbed and becomes over-reactive during the waking day (1). In other words, sleep deprivation can lead to a heightened sensitivity of the amygdala. For example, your roommate’s incessant pencil tapping that normally seems bearable when not sleep deprived, may be particularly annoying after a night of little to no sleep.

Sleep deprivation may reduce attentional focus on positive materials.

Moreover, sleep deprivation may influence emotional memory. For example, researchers gave participants a series of positive, negative, and neutral words to study. They found that those who were sleep deprived remembered fewer positive words than those who were well-rested (1). This suggests that sleep deprivation may reduce attentional focus on positive materials. Furthermore, it has also been found that connectivity between the amygdala and control center of the brain, the prefrontal cortex, is reduced when sleep deprived (2). Reduced feedback from the prefrontal cortex may lead to amygdala overactivity when sleep deprived.

Sleeping through the night or over several nights gradually reduces one’s response to feel upset when recalling a negative experience.

Considering that sleep deprivation impairs the ability to remember positive information, it is closely linked with depression. It is thought that obtaining sufficient sleep causes reductions in the emotional response to negative memories by reducing the response of the amygdala. In other words, sleeping through the night or over several nights gradually reduces one’s response to feel upset when recalling a negative experience. For example, after sleeping, you may be able to remember when your first pet passed away, or when you scored poorly on an exam, without feeling emotionally crippled by the memory. Sleep reduces emotional reactivity to memories.

Experimental research found that sleep deprivation caused a near 30% increase in anxiety symptoms.

In addition to an increased susceptibility to negative emotion, sleep deprivation is closely linked with anxiety. Indeed, recent experimental research found that sleep deprivation caused a near 30% increase in anxiety symptoms (3). For example, suddenly hearing a loud noise, such as an alarm, leads to fear as an initial reaction. You may feel your heart pound through your chest; your pupils may dilate; and you might look around to locate the noise. However, once you realize that it is only a test for the warning alarm systems, you will quickly resume to your work. However, if you’re sleep deprived, this process may happen a bit more slowly. It may take longer for your brain to process the fact that it’s only a warning alarm. Your increase in heart rate may persist, and you may feel anxious for longer than someone who is not sleep deprived. Thus, anxious feelings will likely be intensified when you are in a sleep-deprived state.

Failing to sleep intensifies emotional responses at the neural level. Brain structures involved in emotional processing and cognitive control, particularly the amygdala and prefrontal cortex, are functionally altered by sleep deprivation. Although the life of a student is a demanding one, sleep should be prioritized in order to thrive and function with peak psychological health. So if you’re feeling crappy, try getting a good night’s sleep.

References

1.Walker, M. P., & van der Helm, E. (2009). Overnight therapy? The role of sleep in

emotional brain processing. Psychological Bulletin, 135(5), 731–748.

https://doi.org/10.1037/a0016570

2.Yoo, S., Gujar, N., Hu, P., Jolesz, F. A., & Walker, M. P. (2007). The human emotional

brain without sleep – a prefrontal-amygdala disconnect. Current Biology, 17(20), 1–8.

https://doi.org/10.1016/j.cub.2007.08.007

3. Anwar, Yasmin. “Chronically anxious? Deep sleep may take the edge off.” Retrieved from: https://news.berkeley.edu/2018/11/06/chronically-anxious/

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About Author

Emily Hokett is a PhD student in the Psychology department. She studies relationships among sleep quality, circadian rhythm, memory, and aging. In her free time, she enjoys writing, running, cycling, and power lifting.

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  Timothy Durham was convicted of rape when a test showed his DNA genotype matched the DNA recovered from the crime scene. Eye witnesses testified that Durham was in a different state at the time of the incident, but he wasn’t exonerated from his 3000 year sentence until follow up DNA analysis showed that the preliminary forensic analysis used in the trial was misinterpreted (Thomas et al.). DNA testing serves an invaluable part in our criminal justice system, but it comes with complications and bias that can lead to wrongful convictions and misinformed juries.  

Background:

Forensic genetics aims to identify the origin of a biological sample. It can be traced back to Karl Landsteiner who discovered human ABO blood groups. With blood groups, suspects could be eliminated based on their blood type. For example, if a suspect had type A blood and there was type B blood left at the scene by the perpetrator, the investigators could rule out the suspect. Unfortunately, the reverse didn’t work. If the suspect and perpetrator both had the same blood type, it can’t be concluded that the suspect was guilty. Blood identifiers evolved into 8 distinct categories which improved the ability to eliminate suspects, but could only conclude that (if the system matched) it might be the perpetrator or this person might be related to the perpetrator (Jobling and Gill). The field evolved in the 1980s with the discovery of Minisatellites, lines of repetitive DNA that don’t encode proteins. Minisatellite patterns in DNA create what we know today as the DNA fingerprint, and it has a much higher accuracy rate than previous methods (Augustyn et al.). Around the same time, a breakthrough for victims of sexual assault was discovered. In the case of assault, bodily fluids of both the victim and the assaulter can get mixed. A process called differential lysis was created which could selectively increase the concentration of sperm in a fluid sample thereby allowing for accurate DNA testing (Jobling and Gill). Forensics evolved to use single-locus probe testing after several years because of its ease of interpretation. It looked at specific minisatellites that had high variability between subjects. This was the first DNA-based method to be used in a criminal investigation. Two murder homicides from several years apart were connected using DNA evidence. The evidence was then used to exonerate an innocent man, and the guilty party was found when he tried to evade mandatory DNA testing for all men in the small town. His guilt was then reinforced when the DNA profiles matched, and he gave a confession (Jobling and Gill). Finding DNA at a crime scene doesn’t guarantee that you’ll find a murderer. There are issues with non-pure samples and limited samples that make DNA work difficult, and accreditation of facilities and new techniques and take time (Jobling and Gill).  

Subjectivity of DNA Interpretation:

In a 2009 publication, the National Academy of Science discusses the possibility for subjective influence in lab based forensics. The interpretation bias happens in complex cases where, for example, there could be a mixture of DNA. A study published in 2011 looked specifically at this issue. A gang rape happened in Georgia, and the mixture in DNA from the case was used to prosecute one suspect after another suspect took a plea bargain to testify against him. With DNA mixtures, there are three possible conclusions: suspect excluded, suspect cannot be excluded, and inconclusive. If the suspect is excluded, it means that there’s little to no possibility that his DNA is part of the sample. If the suspect cannot be excluded, it means that there’s a possibility that his DNA is part of the sample. In the trial, the DNA examiners who knew the context of the case concluded that the suspect being prosecuted could not be excluded. The 2011 study gave the DNA evidence from this case and the DNA profiles of the suspects to 17 forensic examiners. These examiners had no context of the case, and they all worked independently. Of the 17, only 1 came to the same conclusion (suspect cannot be excluded) as the examiners who knew the context of the case. Twelve of the 17 concluded that the suspect who was prosecuted and convicted had no relation to the DNA found in the sample. Not only does this show that subjectivity occurs due to the context of the case, but the 17 examiners came up with different findings based on their past experiences meaning that not all DNA analysis is objective. Some organizations like the Scientific Working Group on DNA Analysis Methods say that quantitative statistical evidence should be presented with every categorical conclusion, but the US doesn’t require this (Dror and Hampikian).

False Positives:

There are two categories that cause wrongful identification in a DNA report: coincidental matches and false positives. Coincidental matches are DNA matches between two unrelated people. The probability of these matches is about 1 to 500,000 for white individuals and about 1 to 350,000 for black individuals. This small probability of coincidental matches makes people feel confident in DNA evidence. False positives, on the other hand, are matches between DNA and test DNA that result from issues in the forensics lab. There have been multiple cases of forensics labs accidentally switching victim and suspected rapist DNA which lead to convictions that were later overturned when the lab realized the error. There are also cases of misreading or misunderstanding a sample. In a case from 1993, a man was convicted of rape because someone interpreted a mixed sample of victim and perpetrator DNA as an individual sample. The conviction was again overturned. To prevent false convictions, retesting DNA is allowed, but it’s not an efficient solution. Many people are pushing for statistical information on the probability of false positives, so that the jurors can make accurate judgements based on DNA evidence (Thomas et al.).  

Conclusion:

DNA analysis is a useful tool for the criminal justice system, but subjectivity can be an issue in forensic testing. To combat wrongful convictions, there are organizations like The Innocence Project who use DNA testing to free the innocent, but reformed forensic testing standards should be put in place to prevent subjectivity and to ensure juries are correctly informed during trials. https://www.innocenceproject.org/    

Citation:

Augustyn , Adam, et al. “DNA Finerprinting.” Encyclopedia Britannica , 26 Apr. 2018, www.britannica.com/science/DNA-fingerprinting#ref153186. Dror, Itiel E., and Greg Hampikian. “Subjectivity and Bias in Forensic DNA Mixture Interpretation.” Science & Justice, vol. 51, no. 4, 2011, pp. 204–208., doi:10.1016/j.scijus.2011.08.004. Jobling, Mark A., and Peter Gill. “Encoded Evidence: DNA in Forensic Analysis.” Nature Reviews: Genetics, vol. 5, no. 10, Oct. 2004, pp. 739–751., doi:10.1038/nrg1455. Thompson, William C, et al. “How the Probability of a False Positive Affects the Value of DNA Evidence.” Journal of Forensic Sciences, vol. 48, no. 1, Jan. 2003, pp. 1–8., doi:10.1520/jfs2001171.